Pump



SePt- 18, 1934- N. E. GUNDERsoN 1,974,183

PUMP

Filed Dec. 23, 1929 Patented Sept. 18, 1934 j UNITED STATES levain PATENT OFFICE 6 Claims.

The invention relates generally to motor driven pumps and more particularly to a pump adapted for use while the pump and its driving motor are submerged in a well.

Various attempts have been made to produce a satisfactory pump of this character by means of enclosing the entire motor but it has been found that the motor bearing through which the rotating shaft passes to the pump impeller permits the passage of water, the amount of water admitted to the motor housing becoming greater as the pump is used. To meet this condition operators have attempted to exclude the water from the motor housing by means of compressed air supplied to the motor housing. This practice has not been satisfactory however, because of the increased amount of equipment required in the form of air compressors,

The primary object ofthe present invention is to provide a motor operated pump adapted to be submerged as a unit and embodying means whereby water may be excluded from the vulnerable parts of the motor during prolonged per'iods of use.

Another object is to provide a motor operated pump in which the stator of the motor is completely enclosed by a metallic casing which will prevent leakage ofrwater into the stator windings.

Another object is to provide a motor operated pump wherein the stator is Aenclosed in a watertight casing of such a construction that the einciency of the motor is substantially unaffected.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, in which Figure 1 is a. central vertical section taken through a motor operated pump unit embodying the preferred form of the invention.

Fig. 2 is an enlarged fragmental horizontal section taken along the line 2--2 of Fig. 1.

Fig. 3 is a fragmental development of the inwardly facing annular surface of the stator.

Fig. 4 is a vertical section through a well showing the preferred form of pump unit in its operating position.

While I have shown in the drawing and will herein describe in detail the preferred embodiment of the invention, it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but aim to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

In the drawing, the invention is illustrated in its preferred form as embodied in a motor driven pump unit l0 adapted to be operated submerged as shown in Fig. 4. The unit comprises gener ally a tubular housing or casing providing separate compartments for the motor and the pump 50 impeller and a passageway therethrough for the water or other liquid being pumped. The casing has an annular wall 1l provided with a plurality of vertical ducts or passages 14 arranged to communicate with the impeller chamber 14a 65 at the lower end of the casing and to connect with a discharge opening at the upper end of the cas-` ing.

In the form illustrated, the motor is positioned above the pump and a transverse wall is provided intermediate the motor and pump compartments comprising an inwardly extending flange 15 formed integrally with the wall 1l of the casing and a plate 16 which is removably secured thereto. The upper end of the motor compartment is closed by a dome-shaped hollow member 17, secured within the upper end of the casing. The dome-like upper surface of this memberserves as the inner wall of an outlet pas sage 18 which communicates with the vertical 30 passages 14 in the casing wall 11, the outer wall of the passage 18 comprising a fianged collar 19 bolted to the upper end of the casing 11.

The motor is preferably of the squirrel cage in duction type and has a rotor 20 and a stator 30 g5 which are mounted within the housing formed by the casing wall 11 and the end closures 16 and 1'7. The rotor is preferably provided with cast end rings 21 formed integrally with a plurality of rotor bars 22 and is supported upon a vertical 90 shaft 23 which is rotatably mounted in bearings 24 and 25 carried on said closures. The lower end of the shaft projects through the closure plate 16, for connection with a centrifugal pump impeller 26. The impeller is positioned beneath the plate and in the pump chamber 14a, the lower ends of the passages 14 in the casing being curved inwardly so as to receive water from the impeller passages 26B.

The rotating structure comprising the motor shaft 23, the rotor 20 and impeller 26 is supported by means of a thrust bearing 27 positioned beneath the impeller and engaging the under surface thereof. This bearing, as well as the radial bearings 24 and 25, is preferably formed 105 of a material which. will be lubricated by the liquid being pumped. In the preferred embodiment of the invention which is intended primarily for pumping water, these bearings are formed of rubber. Thus the thrust bearing 27 110 serves not only as a means for supporting the rotating structure but also as a wear or labyrinth ring. During operation of the pump, the impeller generally has a pressure at the outlet end of the passages 26l greater than thatl at the intake end of the passages so that there is a tendency for water to flow down between the circumference of the impeller and the side wall of the chamber 14. In the construction herein disclosed the member 27 not only serves to prevent an excessive down ow or leakage of water but furthermore serves as a thrust bearing and utilizes the unavoidable leakage as a lubricant.

It will be apparent that when the pump is in operation the bearing 25 at the lower end of the shaft will be subjected to water under pressure. To prevent any water which may leak through this bearing from damaging the stator coils 31, an annular wall or closure 33 is provided within the casing to form, with the casing walla of the motor housing, a water tight chamber 34 in which the stator 30 and its stator coils 31 are positioned. The chamber thus formed is particularly adapted for excluding water from the coils 31 since it does not have any moving parts extending into it and about which water might leak. Furthermore, since the closure extends through the motor air gap, it not only prevents water from reaching the exposed end portions of the stator winding but also prevents water from reaching the winding by passing between stator laminations.

The wall 33 is preferably metallic and is joined at its lower end to the edge of the inturned flange 15 of the motor housing by welding or some similar process by which a water-tight joint may be produced. At its upper end the wall 33 is turned outwardly and is similarly joined to the side wall 11 of the casing. The portion which is positioned in the air gap may be in the form of a layer or coating on the stator laminations and spaced from the rotor.

In order that the motor emciency may be main'- tained as nearly as possible at its maximum theportion or section 35 of the closure which is positioned intermediate the rotor and the stator, is of such a construction and material that the characteristics of the magnetic circuit and stator core are not altered appreciably. To attain this end the section 35 of the wall 33 is preferably quite thin, and in close contact with the stator and in addition, is formed from a substantially non-magnetic material'having a high electrical resistance so as to prevent flux leakage and excessive eddy currents.

Although other materials may meet these requirements, it has been found that Roses metal is of particular advantage in forming the section 35. Rose's metal is composed of approximately 22 per cent of tin, 28 per cent of lead, and 50 per cent of bismuth. This metal is diamagnetic, and has a resistance of 64.5 microhms per cubic centimeter at 0 centigrade as compared with 11.8 microhms for soft steel. Thus its effect upon the characteristics of the magnetic circuit and the stator core will be negligible. The use of Rose's metal is also of particular advantage in forming the section 35 since it has a melting point of approximately centigrade and may be cast in place on the stator 30, so as to be firmly interlocked therewith. This casting operation does not effect or deteriorate the stator, since it is well known that in standard practice this element of the motor may be heated to and maintained at a temperature of 110 centigrade without undue deterioration of the windings.

Upon solidication, Rose's metal'expands, while the stator will. of course, contract, so that the metal will fill the wedge-shaped portions 30b of the coil slots and be firmly fixed in place in intimate contact with the stator laminations and the wedges 30 which hold the coils in the'slots. Since the stator may be maintained at a temperaure of 110, the time-of solidication of the casting may be prolonged so that a perfect casting may be obtained.

When the section 35 is formed in the manner above described, the joints between the section 35 and the other portions of the wall 33 are made water-tight by means of a soldering, brazing or other similar operations to form a metallic joint therebetween and after the casting has cooled. the inner surface thereof may be machined so as to provide a uniform clearance between it and the rotor 20.

While the walls about the stator will effective-V ly prevent leakage of water into the chamber 34 enter the chamber. The provision of such a supply of oil requires but a slight'amount of additional equipment so that the added cost of operation is practically negligible. Thus, as shown in Fig. 4 of the drawing, oil is supplied to the chamber 34 through a conduit 36 which extends down to the pump when in use and communicates with the chamber 34 through a hole 37 (Fig. 2) in the casing 11. This conduit houses the wires 38 which are connected to the stator coils 3l. The conduit 36 extends to a point above the water surface so that the stator and all of the electrical connections will be effectively protected from water damage.

To prevent passage of water into the chamber, the oil therein is maintained slightly above the pressure of the water tending to enter the chamber, and in most instances the required pressure may be obtained without the use of additional pumping equipment. 'I'he use of oil under such a pressurein the stator chamber 34 prevents passage of water thereinto, and in case a leak develops in the walls of the chamber, its presence will become known at once due to the presence of oil in the well and in the water being pumped. When such oil is noticed. the pump may be removed from the well and the leak repaired before the stator has been damaged.

From the foregoing it will be apparent that the invention provides a pump wherein the stator coils are effectively guarded against water damage in such a. manner that the elllcierryof the motor is maintained. Furthermore, the bearings for the rotating structure and the means employed to guard the stator coils are of such a character that the motor may be operated under water for long periods of time. It will also be seen that by filling the chamber about the stator with an insulating liquid or oil which does not cause deterioration of the coils, a pressure may be maintained in the chamber which will act as an additional safeguard against the entrance of water.

Although the annular tubular wall formed around the stator is herein described as having the air gap section formed from Rose's metal by casting it in place on the stator, it is to be understood that the wall or section could be formed from other materials and by a different method without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

l. A pump of the character described comprising, in combination, a tubular casing, transverse walls in said casing spaced from the ends thereof to define a motor housing in the casing, said casing having a passage extending longitudinally therethrough past the housing, an impeller for pumping water through said passage, said impeller being mounted in one end of the casing outside of said housing, a motor mounted within said. housing comprising a laminated stator, a rotor and a rotor shaft journaled in the transverse walls of said housing, said shaft projecting through one transverse wall of said housing and being connected to said impeller so as to drive the same, and a closure within the housing arranged to form, with parts of said housing, a water-tight chamber about said stator, said closure including a section positioned between said rotor and said stator in intimate contact with said stator and formed from a substantially non-magnetic metal having a high coefcient of electrical resistance which metal is cast in place so that portions thereof interengage with irregularities in the stator to hold said section in place.

2. A submersible pump comprising a casing having a passage extending longitudinally through a wall thereof, plates extending transversely of said casing in spaced relation to each other to define a motor housing therein, a motor within said housing having a`stator carried by the side walls of the housing and having a rotor with a vertical shaft journaled in said plates and projecting through the lower one of saidplates, a pump impeller on the projecting end of said shaft, a thrust bearing beneath said impeller, and a lower end wall supporting said bearing and removably secured'to the lower end of said casing.

3. A pump of the character described comprising a cylindrical casing adapted to be supported in vertical position and having a passage extending longitudinally through the wall thereof, a first removably mounted plate extending across the casing, in spaced relation to the upper end thereof to form onev end of a motor housing, means including a second removably mounted plate extending across the casing in spaced relation to the lower end of the casing to form the other end of bearing.

the motor housing, a motor within said housing having a stator secured to the wall of the housing, a rotor for said motor having a vertical shaft journaled in said plates and projecting through said lower plate, said rotor being withdrawable from said housing when said second plate is detached, a pump impeller within the lower end of said casing and having a driving connection with the projecting end of said shaft, an end wall removably secured to said lower end of the casing, and a thrust bearing carried by said removable wall for supporting said shaft, said pump impeller being removable from said casing when said end wall is removed.

4. A pump of the character described comprising a casing having a passage therethrough and providing a motor housing, a motor in said housing, a rotor for said motor having a vertically positioned shaft, radial bearings for said shaft, a pump impeller on said shaft, a thrust bearing for said shaft located adjacent to the lower end thereof and arranged to be lubricated by the liquid being pumped, and a removable lower wall for said casing arranged to carry and support said thrust 5. A pump of the character described comprising, in combination, a casing having a passage therethrough and providing a motor housing, a motor in said housing, a rotor for said motor having a vertically positioned shaft, radial bearings for said shaft, a pump impeller on the lower end of said shaft, a thrust bearing positioned beneath and engaging said impeller to support the rotating parts, said bearing being of a material lubricated by the liquid being pumped and serving as a wear ring to prevent excessive leakage from the discharge end of the impeller back to the suction end.

6. A pump of the character described comprising a casing having a passage therethrough with an intake at its lower end and providing a motor housing, a motor in said housing, a rotor for said motor having a vertically positioned shaft, radial bearings for said shaft, a pump impeller on the lower end of said'shaft and operating to draw 120 water through said intake and pump it through said passage, and a rubber ring thrust bearing positioned beneath the impeller and surrounding said intake and engaging the impeller to support the rotating parts.

NORRIS E. GUNDERSON. 

